1. Field of the Invention
This invention relates to a system for sensing the irregularities, such as bumps and pot holes, in a road surface and modifying an operational system of the vehicle, such as the suspension system, and thereby the running performance of the vehicle, according to the type and severity of the sensed irregularity.
2. Discussing of Prior Art
In one known road surface sensing proposal, described in U.S. Pat. No. 4,781,465, the road surface is scanned by directing a light beam onto the surface at a predetermined distance ahead of the vehicle and monitoring the distance travelled by the reflected light to produce a signal used for suspension adjustment. The operation of such a system can be seriously disturbed by the effect of spurious reflections and the preventive and corrective expedients necessary to deal with such problems further increase the manufacturing costs of an already inherently expensive system.
In another known system, described in U.S. Pat. No. 4,225,950, ultrasonic sound emissions are directed onto a road surface and reflected signals are used to influence vehicle performance. The ultrasonic sound signals are, however, very susceptible to degradation by air turbulence and such systems are therefore considered to be unreliable.
It has also been proposed to use radar to measure variations in the distance between the underside of a vehicle and road surface thereunder and to produce corresponding control signals. However, such a system does not provide sufficient response time to enable the controlled equipment on the vehicle to modify the vehicle performance in a satisfactory manner.